scholarly journals Establishing the relative importance of sympatric definitive hosts in the transmission of the sealworm, Pseudoterranova decipiens: a host-community approach

2001 ◽  
Vol 3 ◽  
pp. 161
Author(s):  
F Javier Aznar ◽  
Juan A Balbuena ◽  
Mercedes Fernández ◽  
J Antonio Raga
Keyword(s):  
Host Community ◽  
Harp Seal ◽  
Harbour Seal ◽  
Transmission Model ◽  
Relative Importance ◽  
Geographic Scale ◽  
Hooded Seal ◽  
Pseudoterranova Decipiens ◽  
Seal Population

The importance of a given host to a particular parasite can be determined according to three different criteria: host preference, host physiological suitability and host contribution to transmission. Most studies on the sealworm Pseudoterranova decipiens have focussed on the latter factor, but few attempts have been made to develop a quantitative transmission model evaluating the relative importance of each host. The purpose of this study was to propose a flow-chart model to study sealworm transmission within a seal community. The model was applied to hypothetical data of four seal species acting as definitive hosts of P. decipiens sensu stricto in eastern Canada: harp seal Phoca groenlandica, harbour seal P. vitulina, grey seal Halichoerus grypus and hooded seal Cystophora cristata. The dynamics of the model was studied using population estimates from 1990 to 1996. To illustrate the interrelationship of the seal populations in the flow dynamics, the model’s behaviour was explored by manipulation of the harp seal population size. The results showed that grey seals accounted by far for most transmission from and to the seals. The harbour seal population also sustained a biologically significant proportion of the flow, whereas the role of hooded and harp seals seemed negligible despite their large population sizes. The hypothetical removal of the harp seal population resulted in small increases in the relative flows to the other seals. These results conform to previous qualitative assessments on the relative importance of these seal species in sealworm transmission. The model provided some heuristic rules useful to understand transmission patterns. The data suggested that the harbour seal population should be about twice that of the grey seals to account for a larger share of transmission than grey seals. Although this is unlikely to occur at a large geographic scale, harbour seals outnumber grey seals in some areas and, therefore, the role of each host may change locally. To make this approach more realistic, further work should seek accurate estimates of parasite population parameters, better definition of the host community boundaries (at a local scale) and improved control of confounding variables.

scholarly journals Sealworm (Pseudoterranova decipiens) infection in the benthic cottid (Taurulus bubalis) in relation to population increase of harbour seal (Phoca vitulina) in Skagerrak, Sweden

2001 ◽  
Vol 3 ◽  
pp. 47 ◽  
Author(s):  
Sven-Gunnar Lunneryd ◽  
Karl Inne Ugland ◽  
Paul Eric Aspholm
Keyword(s):  
Gadus Morhua ◽  
Final Host ◽  
Infected Fish ◽  
Harbour Seal ◽  
Population Increase ◽  
Threshold Size ◽  
Pseudoterranova Decipiens ◽  
Harbour Seals ◽  
Seal Population ◽  
Benthic Fishes

In Koster archipelago (northern Skagerrak, Sweden) the harbour seal population increased from approximately 350 to more than 1000 individuals between 1988 and 1998. During the same period, sealworm (Pseudoterranova decipiens) abundance in the most heavily infected fish species, bullrout (Myoxocepahulus scorpius) and sea scorpion (Taurulus bubalis), did not increase. Since harbour seals do not normally feed on those cottids an infection route via cod (Gadus morhua), which consume cottids, is proposed. The abundance of sealworm in the final host is therefore related to the probability of cod preying on infected cottids prior to being preyed upon by seals. Our model predictsthat the abundance of larval sealworm in benthic fishes is not related to the number of seals when the colony is over a specific threshold size.

Sensitivity Analysis of Two Harp Seal (Pagophilus groenlandicus) Population Models

1979 ◽  
Vol 36 (4) ◽  
pp. 404-410 ◽  
Author(s):  
R. K. Mohn
Keyword(s):  
Sensitivity Analysis ◽  
Population Model ◽  
Maximum Sustainable Yield ◽  
Population Models ◽  
Harp Seal ◽  
Sustainable Yield ◽  
Relative Importance ◽  
Yield Level ◽  
Pagophilus Groenlandicus ◽  
Seal Population

Sensitivity analysis has been used to estimate the relative importance of input parameters both between and within two harp seal (Pagophilus groenlandicus) population models. The population size at maximum sustainable yield is shown to be much more poorly defined than the yield level itself. Key words: sensitivity analysis, harp seal, population model, sustainable yield, management

Population Control (Review Article)

1961 ◽  
Vol 1 (3) ◽  
pp. 89-98
Author(s):  
Karol J. Krotki
Keyword(s):  
Population Control ◽  
Review Article ◽  
Small Enterprise ◽  
Opportunity Costs ◽  
Relative Importance ◽  
Factual Information ◽  
Undue Influence ◽  
Clear Cut ◽  
Economic Considerations

Discussions about the role of small enterprise in economic development tend to remain inconclusive partly because of the difficulty of assessing the relative importance of economic and non-economic objectives and partly because of the dearth of factual information on which to base an economic calculus. It is probably true, moreover, that, because of a lack of general agreement as to the economic case for or against small enterprise, non-economic considerations, including some merely romantic attitudes toward smallness and bigness, tend to exert an undue influence on public policies. There may, of course, be no clear-cut economic case. And noneconomic considerations should and will inevitably weigh significantly in policy decisions. If, however, some of the economic questions could be settled by more and better knowledge, these decisions could more accurately reflect the opportunity costs of pursuing non-economic objectives.

scholarly journals Role of propagule pressure in colonization success: disentangling the relative importance of demographic, genetic and habitat effects

2013 ◽  
Vol 26 (8) ◽  
pp. 1691-1699 ◽  
Author(s):  
R. A. Hufbauer ◽  
A. Rutschmann ◽  
B. Serrate ◽  
H. Vermeil de Conchard ◽  
B. Facon
Keyword(s):  
Propagule Pressure ◽  
Relative Importance ◽  
Colonization Success

scholarly journals Model-based evaluation of school- and non-school-related measures to control the COVID-19 pandemic

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Ganna Rozhnova ◽  
Christiaan H. van Dorp ◽  
Patricia Bruijning-Verhagen ◽  
Martin C. J. Bootsma ◽  
Janneke H. H. M. van de Wijgert ◽  
...  
Keyword(s):  
Reproduction Number ◽  
Additional Benefit ◽  
Transmission Model ◽  
Time Points ◽  
School Based ◽  
Admission Data ◽  
Age Structured ◽  
The Impact ◽  
Pandemic Wave

AbstractThe role of school-based contacts in the epidemiology of SARS-CoV-2 is incompletely understood. We use an age-structured transmission model fitted to age-specific seroprevalence and hospital admission data to assess the effects of school-based measures at different time points during the COVID-19 pandemic in the Netherlands. Our analyses suggest that the impact of measures reducing school-based contacts depends on the remaining opportunities to reduce non-school-based contacts. If opportunities to reduce the effective reproduction number (Re) with non-school-based measures are exhausted or undesired and Re is still close to 1, the additional benefit of school-based measures may be considerable, particularly among older school children. As two examples, we demonstrate that keeping schools closed after the summer holidays in 2020, in the absence of other measures, would not have prevented the second pandemic wave in autumn 2020 but closing schools in November 2020 could have reduced Re below 1, with unchanged non-school-based contacts.

scholarly journals The Arctic as a “Strategic” and “Important” Chinese Foreign Policy Interest: Exploring the Role of Labels and Hierarchies in China’s Arctic Discourses

2021 ◽  
pp. 186810262110186
Author(s):  
Patrik Andersson
Keyword(s):  
Foreign Policy ◽  
International Relations ◽  
Political Discourse ◽  
Chinese Foreign Policy ◽  
The Arctic ◽  
Relative Importance ◽  
Precise Understanding ◽  
New Frontier ◽  
Political Priority

Research confirms that China is becoming more engaged in the Arctic. However, international relations scholarship often extrapolates from relatively few instances of activity to wide-ranging claims about Chinese priorities. Fortunately, Chinese political discourse is organised by labels that allow us to study how the Arctic is classified and ranked along China’s other foreign policy priorities. This article analyses two such classifications – “important maritime interest” and “strategic new frontier,” exploring how they have come about, what they mean, and how they add political priority to the Arctic. It argues that hierarchies are constructed in two ways: by adding gradients and by including/excluding categories of priority. It views categories as performative: they not only convey information about character and relative importance of interests but are also used for achieving different objectives. By focusing on foreign policy classifications, the article contributes to a more nuanced and precise understanding of China’s Arctic interests.

Study of the role of Chlamydia, Mycoplasma, Ureaplasma and other microaerophilic and aerobic bacteria in uterine infections of mares with reproductive disorders

2003 ◽  
Vol 51 (1) ◽  
pp. 45-52 ◽  
Author(s):  
László Szeredi ◽  
M. Tenk ◽  
I. Schiller ◽  
Keyword(s):  
Pathogenic Bacteria ◽  
Anaerobic Bacteria ◽  
Aerobic Bacteria ◽  
Relative Importance ◽  
Reproductive Disorders ◽  
Taylorella Equigenitalis

In six healthy mares and 24 mares showing reproductive disorders swab samples were taken from the fossa clitoridis to isolate Taylorella equigenitalis, and from the uterus to isolate mycoplasmas, ureaplasmas and other aerobic bacteria. Swab samples were also taken from the uterus for Chlamydiaantigen ELISA and ChlamydiaPCR studies. The uterus of 27 mares was examined cytologically, and biopsy samples were taken from the endometrium for histological examinations and for immunohistochemical examinations aimed at the detection of chlamydiae. T. equigenitalis, mycoplasmas, ureaplasmas and chlamydiae could not be detected from any of the mares examined. Aerobic facultative pathogenic bacteria were isolated from mares with endometritis in four cases. In 18 out of 22 mares with endometritis (82%) no infective agents could be demonstrated. Further studies are needed to elucidate the relative importance of non-infectious causes of endometritis and of anaerobic bacteria often detectable in the uterus in the aetiology of the reproductive disorders observed.

scholarly journals Do patients value a hospital’s innovativeness reputation? A multi-method approach to assess the relative importance of innovativeness reputation in patients’ hospital choice

2017 ◽  
Vol 31 (3) ◽  
pp. 138-153 ◽  
Author(s):  
Sebastian Gurtner ◽  
Nadine Hietschold ◽  
María Vaquero Martín
Keyword(s):  
Value Added ◽  
Patient Choice ◽  
Relative Importance ◽  
Hospital Choice ◽  
Patient Decision ◽  
Technical Innovations ◽  
Multi Method Approach ◽  
Method Approach

Innovations in health care are costly and risky, but they also provide the opportunity for hospitals to increase quality of care, to distinguish themselves from competitors and to attract patients. While numerous hospitals strive to increase their innovativeness by adopting a costly innovation leader strategy, the question of whether this actually influences the patient’s choice remains unanswered. To understand the role of innovativeness from the patient perspective, this study conceptualizes the construct of innovativeness reputation of hospitals and determines its relevance in patients’ hospital choice decisions. In the pretest, we identified six dimensions of innovativeness reputation such as progressive work procedures and value added services. We then used three different quantitative multi-criteria decision-making methods to evaluate the relative importance of innovativeness reputation in patient choice. We collected data from 355 former German patients who had undergone elective non-emergency surgery. Overall, innovativeness reputation accounts for 11.6%–16.8% of the patient decision. Innovativeness reputation has a moderate influence on hospital choice and should be taken into account by managers. Since technical innovations are costly, hospitals should use other means to enhance their innovative image. Strategies such as emphasizing value added services can enable hospitals to increase their innovativeness reputation efficiently.

scholarly journals A Gnotobiotic Model to Examine Plant and Microbiome Contributions to Survival under Arsenic Stress

2020 ◽  
Vol 9 (1) ◽  
pp. 45
Author(s):  
María del Carmen Molina ◽  
James F. White ◽  
Sara García-Salgado ◽  
M. Ángeles Quijano ◽  
Natalia González-Benítez
Keyword(s):  
Seedling Growth ◽  
Endophytic Bacteria ◽  
Root Hairs ◽  
Resistant Bacteria ◽  
Relative Importance ◽  
Early Stages ◽  
Bacterial Interaction ◽  
Arsenic Stress ◽  
Free Media

So far, the relative importance of the plant and its microbiome in the development of early stages of plant seedling growth under arsenic stress has not been studied. To test the role of endophytic bacteria in increasing plant success under arsenic stress, gnotobiotic seeds of J. montana were inoculated with two endophytic bacteria: Pantoea conspicua MC-K1 (PGPB and As resistant bacteria) and Arthrobacter sp. MC-D3A (non-helper and non-As resistant bacteria) and an endobacteria mixture. In holobiotic seedlings (with seed-vectored microbes intact), neither the capacity of germination nor development of roots and lateral hairs was affected at 125 μM As(V). However, in gnotobiotic seedlings, the plants are negatively impacted by absence of a microbiome and presence of arsenic, resulting in reduced growth of roots and root hairs. The inoculation of a single PGPB (P. conspicua-MCK1) shows a tendency to the recovery of the plant, both in arsenic enriched and arsenic-free media, while the inoculation with Arthrobacter sp. does not help in the recovery of the plants. Inoculation with a bacterial mixture allows recovery of plants in arsenic free media; however, plants did not recover under arsenic stress, probably because of a bacterial interaction in the mixture.

ROLE OF REINFECTION IN TRANSMISSION DYNAMICS OF COVID-19: A SEMI-ANALYTICAL APPROACH USING DIFFERENTIAL TRANSFORM METHOD

2021 ◽  
Vol 6 (1) ◽  
pp. 745
Author(s):  
Opeyemi Odetunde ◽  
Jibril Lawal ◽  
Ally Yeketi Ayinla
Keyword(s):  
Treatment Strategies ◽  
Differential Transform Method ◽  
Host Community ◽  
Transmission Dynamics ◽  
Transform Method ◽  
Social Distancing ◽  
Linear System Of Equations ◽  
Differential Transform ◽  
Non Linear System

Reinfection of a recovered individual either as a result of relapse or new contact no doubt poses a major threat to the eradication of an infection within the host community. In this work, the role of re-infection in the transmission dynamics of COVID-19 was considered and analysed using the semi-analytical tool Differential Transform Method (DTM). COVID-19 (also known as Coronavirus) has shut down the economy of the world since it became a global pandemic. A mathematical model was constructed with consideration of multiple pathways of infection transmission, the treatment strategies and policies adopted (social distancing, wearing of face mask and so on) to limit the spread of the infection globally. The non-linear system of equations governing the model was solved using DTM and the resulting series solution was compared with the standard numeric Runge-Kutta order 4 (RK4). It was discovered that re-integration of a recovered individual into the susceptible community without observing the prevention guidelines such as social distancing, washing of hands and proper sanitizing could increase the spread of the infection since the recovered individuals are not guaranteed of immunity against the infection after recovery. The study concluded that families of recovered patients must ensure adequate preventive measure while integrating their recovered loved ones back to their midst.

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